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I am writing code to DMA out of the the SPORT port 3 bytes every 138.9usec (7200 times a second). I am using TIMER0 to generate an interrupt at 138.9usec, the interrupt service routine sets up the DMA transfer of 3 bytes if data and initiates the transfer. Timing of the interrupt proves that this is going off at 7200Hz, but the Long Frame being used in the DMA transfer goes high between 2.8usec and 5.4 usec later. What would cause the variation in the time of the Frame going high? I have no other interrupts set and the input clock is 24MHz. Any information would be greatly appreciated. Thanks |
21065L DMA delay
Started by ●September 26, 2002
